EXTRACELLULAR 2-CHLOROADENOSINE AND ATP STIMULATE VOLUME- SENSITIVE CL- CURRENT AND CALCIUM MOBILIZATION IN HUMAN TRACHEAL 9HTEO- CELLS

The perforated-patch whole-cell technique was used to record membrane currents in epithelial cells (9HTEo-) obtained from the human tracheal epithelium. Extracellular application of 2-chloroadenosine and ATP (0.01-100 microM) caused activation of Cl- currents similar to those regulated by cell volume in airway and intestinal cells. This response was inhibited by increasing extracellular osmolality, by omission of extracellular Ca2+, or by the addition of the A2 adenosine receptor antagonist 3,7-dimethyl-1-propargylxanthine (DMPX). Fluorimetric measurements with fura-2 reveal that 2-chloroadenosine and ATP elicited both a Ca2+ influx through the plasma membrane and a release from intracellular stores.